Feel a bit self-conscious replying to this thread as it really doesn't affect the price of monkeys.
However my attitude to it is; if your on the ground as aircrew in a flying related job/task (S Nav O, CAOC, Flying display coordinator etc) then it is highly appropriate to wear your flying suit.
Throughout the history of uniformed forces, the recognisability of your function in life by the manner of your uniform has been an important and practical issue, eg red flashes and cap-bands for army staff officers, white caps for the scuffers and so on.
However if theres no good reason for wearing your green bag then it's time to raid your loft insultion.